Hi, I tried to translate picture's resolution from 10mx10m to 50mx50m using "gdalwarp" command and got the problem. I used it with "-r mode" like this.
$ gdalwarp -t_srs EPSG:4326 -tr 0.000416667 0.000416667 -r mode original.tif resize.tif I thought that "-r mode" resamples specified resolution (in this case, 5x5 pixel), but the outcome was very strange. So I made a test script and checked. (The square that is surrounded (row,col)=(25,25)(74,74) is value 1,and others is value 0,100x100 pixel.) This is the test script using GRASS(7.0.3). # set the resolution 100mx100m and a size is 100x100 $ g.region w=140 e=140.0083 s=36 n=36.0083 res=8.333333333333333e-05 $ r.mapcalc " dummy = if(row()>25,if(row()<75,if(col()>25,if(col()<75,1),0),0),0) " $ r.out.gdal input=dummy output=original.tif # And checked. $ gdalwarp -t_srs EPSG:4326 -tr 0.000416667 0.000416667 -r mode original.tif resize.tif On the original.tif,the square that is surrounded (row,col)=(70,70),(75,75) account for 15/25 value 1, but the resize.tif the square that is surrounded (row,col)=(14,14),(15,15) is value 0. Is this the problem of the mode algorithm? The gdal version I used is 1.11.2 and OS is Ubuntu 14.04. Thank you for your replies. Katagi
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